Key technologies for flexible interconnection in urban power grid and pilot demonstration

Abstract

Summary The application of power electronics is an important trend of power system transformation. This paper introduces the world's first flexible interconnection in 220‐kV urban power grid for the first time. This paper presents the key technologies for this project. Firstly, this paper introduces the concept of flexible interconnection, in which the flexible loop operation mode is proposed. Then, this paper introduces the pilot project of partition flexible interconnection in Beijing, China. The project is to build a new flexible DC interconnection based on back‐to‐back modular multilevel converter technology between 2 subtransmission areas in Beijing power supply grid, in order to enhance stability and security. Finally, the project is comprehensively evaluated based on real project data, in which transient voltage stability, static voltage security, total supply capability, short‐circuit current, and reliability are analyzed. The results have shown the effectiveness of the proposed flexible interconnection in large‐scale urban power grid. This project demonstrates a promising application of advanced power electronics in urban power grid.

Frequency selection method for urban low frequency multi‐terminal interconnected systems

“…Based on them, the number of N‐1 fault conditions of partition i on line k can be given as r k,i , which is indexed by j . The specific support power needed in a certain case can be calculated by the method proposed by existing research, such as the sensitivity method in reference [8].…”

“…Partitions interconnection makes power support possible [8][9][10]. For the partition with greater load, in order to prevent the further expansion of the fault, the power support of adjacent partition is of great importance.…”

Locating and sizing of partition flexible interconnection converter station in large urban power grids

“…The capacity design process for ID can be divided into the following steps: Firstly, APD and RPD can be obtained from the results of a simulation in location optimisation stage; Then, according to MVCC (or see (23)), the required capacities at two sides of PFICS corresponding to DRPD are derived, respectively, and initial capacity can adopt the maximum value of APD and these two derived capacities. Finally, the derived capacity should be processed considering the modular design of MMC (see (17)), and the result should leave some margin.…”

“…In recent 20 years, VSC-HVDC technology has been developing so fast that there is an increasing number of applications with respect to flexible interconnection [3][4][5][6][7][8][9][10][11][12][13][14][15][16], which can be categorised into source-network interconnection, networknetwork interconnection and network-load interconnection. Research in this paper is on the basis of 220 kV partition flexible interconnection pilot project, Beijing, China [17]. It belongs to network-network interconnection, which is often seen between asynchronous power grids.…”

Coordinated Control Strategy of CU-MTDC under Abnormal Conditions Considering Power Supply Security

“…However, the control strategy of the DC system is not involved. On the basis of the [10], the detailed control strategy of a back-to-back VSC-HVDC interconnected two load areas of the urban power grid is proposed in [11]. In this paper, the proposed method includes load-balanced control, emergency support control and static voltage control.…”